Apparatus for sealing an annular space

ABSTRACT

Sealing apparatus for sealing the annular space between an inner member and an outer member. A malleable metallic seal ring is disposed between these members, including an axial undulation providing an inner annular crest and an outer annular crest. An axial force imposed on the ring shortens its length, deforming the inner crest into sealing engagement with the inner member and the outer crest into sealing engagement with the outer member.

Hit States atent Nelson [54] APPARATUS FOR SEALING AN ANNULAR SPACE [72] Inventor: Bobby H. Nelson, Houston, Tex.

[73] Assignee: Vetco Offshore Industries, Inc., Ventura,

Calif.

[22] Filed: June 22, 1970 [21] App]. No.: 47,982

Related US. Application Data [62] Division of Ser. No. 772,521, Nov. 1, 1968, Pat. No.

US. Cl ..277/235, 277/165 ..F16j 15/12 Field of Search ..277/235 R, 209, 21 l; 285/18, 285/142; 166/75, 82, 83, 86-89 ,[56] References Cited UNITED STATES PATENTS 1,840,312 1/1932 Dunmire ..277/211 2,119,252 5/1938 Thaheld ..277/235 FOREIGN PATENTS 0R APPLICATIONS 60,739 2/1892 Germany ..277/209 Primary Examiner-Robert 1. Smith AttorneyBemard Kriegel [57] ABSTRACT Sealing apparatus for sealing the annular space between an inner member and an outer member. A malleable metallic seal ring is disposed between these members, including an axial undulation providing an inner annular crest and an outer annular crest. An axial force imposed on the ring shortens its length, deforming the inner crest into sealing engagement with the inner member and the outer crest into sealing engagement with the outer member.

8 Claims, 8 Drawing Figures 3 Sheets-Sheet 1 Patented March 14, 1972 I/vvE/wae.

Base s/ H 4/51. sa/v Patented March 14, 1972 3 Sheets-Shget 3 INvEA/Toe. B0559 H NELSON firrazA/Es APPARATUS FOR SEALING AN ANNULAR SPACE This application is a division of application Ser. No. 772,52l,filed Nov. 1, 1968, for Hydraulically Set Casing Hanger Apparatus and Packing Sleeve, now US. Pat. No. 3,561,527.

In the drilling of oil and gas wells at an underwater site, different casing strings are hung to protect strata that have been drilled from the pressures that may be required or encountered at greater depths. In many cases, a special housing is provided at or near the ocean bottom to support and seal off the casing string cemented in the well bore. With the special housing below water and a drilling rig above water, problems are encountered in supporting the casing string, circulating fluid for conditioning the well, cementing the casing string in the well bore, energizing a seal between the casing hanger and a previously set hanger or head, and, after testing the seal, removing the running tool and pipe on which the running tool is operated.

Particularly, in the case of drilling in deep water, where the pipe on which the running tool is operated must extend a substantial distance from the platform or floating vessel to the ocean floor, the application of high torque for setting conventional seals between the casing hanger and the subsurface housing or previously set casing hanger is objectionable.

The invention provides apparatus in which the seal between an inner body member and an outer housing member may be set by hydraulic pressure, or other nonrotatable axial force applied to the seal.

In accomplishing the foregoing, the apparatus includes a packer or seal in the form of a sleeve or ring adapted to be deformed into sealing engagement with opposing cylindrical walls by the application of an axial force, the packer or sea] comprising a longitudinally undulated, deformable metal body which is deformed beyond its elastic limit when in engagement with the cylindrical walls. In the specifically illustrated embodiment, the packer or seal may also include elastomeric material which is also deformed upon the application of a force to deform the metal body, the elastomeric material engaging the opposing cylindrical walls to insure the prevention of leakage past the metal body.

Another object is to provide a packing or seal device in which a metal body is deformed inwardly and outwardly into effective sealing relation to opposing cylindrical walls.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of several forms in which it may be embodied. Such forms are shown in the drawings accompanying and forming part of the present specification. These forms will now be described in detail for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense.

Referring to the drawings:

FIG. 1 is a view partly in elevation, with parts broken away, and showing a casing hanger and associated apparatus installed in and in association with a well bore underlying a body of water;

FIGS. 2a and 2b together constitute a quarter longitudinal section through casing hanger apparatus embodying the invention and landed in a surrounding hanger body or housing, the parts being illustrated in the initialcondition which they occupy in lowering the apparatus from a drilling rig, FIG. 2b being a downward continuation of FIG. 2a;

FIGS. 3a and 31; together constitute a quarter longitudinal section, generally similar to FIGS. 2a and 2b, but showing the hanger body anchored in the housing or previously set hanger, and the seal or packer deformed and sealing off the space between the hanger and the housing or previously set casing hanger;

FIG. 4 is a transverse section taken on the line 4-4 of FIG. 2b;

FIG. 5 is a fragmentary longitudinal section illustrating the packed-off seal of the invention; and

FIG. 6 is a fragmentary longitudinal section illustrating a modified packed-off seal.

A typical installation of apparatus embodying the invention is illustrated somewhat diagrammatically in FIG. 1 in connection with a well bore A underlying an ocean or other body of water and extending downwardly from the ocean floor F. A suitable base structure B is supported on the ocean floor and carries an outer casing C of relatively large diameter suspended from a casing hanger body or head D resting upon an outer housing seat E on the base and locked thereto by a suitable lock ring G. Disposed within the outer casing is an intermediate string of easing H extending down into the well bore and suspended from a suitable casing hanger body J resting upon a companion tapered seat K in the outer body. One or a stack of blowout preventers N are connected by means of a suitable connector P to the head D, such as by a hydraulic connector illustrated in US. Pat. No. 3,321.2 I 7, for Coupling Apparatus for Well Heads and the Like," the blowout preventers, in turn, being connected by a suitable hydraulic or other connector R to a flexible joint S, made of sections, secured to a marine conductor pipe T extending to the drilling rig, which may be located on a drilling platform or on a floating vessel or structure (not shown). Another string of casing Y is disclosed in FIG. 1 as having been supported in a hanger W locked in packed-off condition in the intermediate hanger body J.

Referring now to FIGS. 2a and 2b, the casing hanger apparatus W includes a body 10 of annular form having a lower hanger thread 11 connected to the downwardly extending casing Y. The casing hanger body 10 has a downwardly facing tapered shoulder 12 adapted to engage an upwardly facing seat 13 in the previously set hanger body J, for example. At its upper end, the hanger body 10 has an internal left-hand threaded section 14 adapted for threaded coengagement by an externally threaded flange 15 on a mandrel 16 of a running tool, generally denoted at Z. At its upper end, the mandrel 16 has an internally threaded box 17 adapted to receive the externally threaded pin end 18 of a running-in string of pipe 19 extending to the drilling rig. Extending longitudinally through the mandrel 16 is a central passage 20 adapted to communicate with the pipe string 19 and the casing Y. 7

Accordingly, it is apparent that the string of easing Y ma be lowered through the body of water and landed in a housing or previously set casing hanger, the downwardly facing shoulder 12 of the hanger body 10 supporting the casing string Y. Thereafter, cement may be displaced downwardly through the pipe string 19 and the mandrel passage 20, and thence downwardly through the casing string Y to the bottom thereof, then upwardly through the annular space 21 between the casing Y and the hanger body J, such fluent cement then passing through longitudinal passages 22 provided in the hanger body 10 and into the space above this hanger body, as is typical in the hanging of casing strings from subsurface housings and previously set liner hangers and the cementing of casings, as herein illustrated.

However, it is desired that the hanger body 10 be anchored in the body J and that the running tool Z be disconnected from the hanger body 10, as well as that the space between the hanger body 10 and the body I be sealed off. Accordingly, the present invention provides anchor means, generally denoted at 23, for anchoring the hanger body 10 within the body J; actuator means, generally denoted at 24, for effecting operation of the anchoring means 23; and seal means, generally denoted at 25, for effecting a seal between the hanger body 10 and the body J and also operable by the actuator means 24.

The mandrel 16 of the running tool Z, at a location spaced above the flange 15, is provided with a lower annular piston 26 projecting outwardly therefrom. Spaced above the annular piston 26 is an upper annular piston 27, which is threaded as at 27a, or otherwise suitably connected, to the mandrel 16. A loading or cylinder sleeve 28 is reciprocably disposed about the piston 27 and the piston 26, suitable side seal rings 29 and 30 being provided, respectively, between the piston 27 and the piston 26 and internal, axially spaced cylindrical walls 31 and 32 of the loading sleeve 28. Internally of and integral with the loading sleeve 28 is an internal annular cylinder head 33 having a sealing ring 34 adapted for sealing engagement with the external cylindrical wall 35 of the tool mandrel 16. This annular head 33 is disposed between the lower piston 26 and the upper piston 27 on the mandrel 16 and divides the annular space 36 between the mandrel and the loading sleeve 28 into a lower annular pressure chamber 37 below the cylinder head 33 and an upper pressure chamber 38 above the cylinder head The tool mandrel 16 is provided with lower annular ports 39 leading from the passage 20 through the mandrel into thelower chamber 37, the mandrel also being provided with upper ports 40 leading from the mandrel passage 20 into the upper chamber 38.

Means are provided for normally closing the lower ports 39 and the upper ports 40 to prevent fluid communication between the mandrel passage 20 and either of the chambers 37 or 38. In the illustrative embodiment, this means comprises a sleeve 41 disposed in the mandrel passage 20 and seating on a lower mandrel shoulder 42 provided within the mandrel passage 20. The sleeve 41 spans both the lower and upper ports 39 and 40, and is provided with suitable side seal rings 43 and 44 spaced above and below the ports 40 and another side seal ring 45 spaced below the lower ports 39. At its upper end, the sleeve 41 has an internal channel or groove 46 providing an inwardly projecting flange 47 adapted to be engaged by a suitable tool (not shown) for engaging the flange 47 and moving the sleeve 41 axially upwardly so as to uncover the ports 39 and 40 during use of the apparatus, as will be hereinafter described, the sleeve 41 being elevated through the pipe 19 to the drilling rig.

At its lower end, the loading sleeve 28 supports the seal means 25. More particularly, the seal means 25 includes a support collar or ring 50, which is detachably secured at its upper end to a reduced diameter end portion 51 on the lower end of the loading sleeve 28, as by means of a suitable number of circumferentially spaced shear pins 52. At its upper end 53, the thrust ring 50 is spaced downwardly from a downwardly facing shoulder 54 on the loading sleeve 28, so as to allow downward movement of the loading sleeve 28 relative to the support ring 50 when it is desired that the pins 52 be sheared during use of the apparatus.

Below the support ring 50, the seal means 25 includes deformable seal means 55, including a longitudinally undulated or waved metallic sealing ring section 56, which is in tegral in the illustrative embodiment with the support sleeve 50, and has at least one inner annular crest 56a and at least one outer annular crest 56b. Molded about the undulated sleeve section 56 is an annular body of rubber or rubber-like, elastomeric material 57, the sleeve section 56 having lateral holes or openings 58 through which the rubber body extends to assist in uniting the rubber with the sleeve section 56.

At its lower end, the undulated sleeve section 56 has the locking means 23 thereon, including a series of downwardly extended circumferentially spaced deformable lock fingers 59. As seen in FIG. 4, these fingers 59 are of such extent circumferentially as to be readily flexed outwardly and are in such number as to positively anchor the casing hanger body against the hanger body seat 13 and to the hanger body J, as well as to anchor the sealing means 25 against displacement after actuation of the seal means and the anchor means, as will hereinafter be described, whereby to effect outwardexpansion of the lock fingers 59 into an annular channel or internal groove 60 formed within the body J. This groove 60 has an outer downwardly and outwardly flaring wall 61 and a lower substantially horizontal wall 63 which, in the illustrative embodiment, is slightly downwardly and inwardly inclined from a true horizontal plane. I

When the casing hanger assembly, including the running tool Z, are to be conditioned to be run into the body J, the seal sleeve 41 will be in place in the mandrel bore 20, closing the ports 39 and 40; and the lower chamber 37 may be pressurized by the application of oil or other fluid thereto under pressure, so as to hold the internal cylinder head 33 of the loading sleeve 28 in an upper position substantially in engagement with the upper piston 27. Such fluid pressure may be applied through a port 37a in the sleeve 28 leading into the chamber 37 from the outside of the loading sleeve 28, and, when the cylinder head 33 is in abutting engagement with the upper piston 27, this port 37a may be closed by a suitable plug 37b which is threaded into an internally threaded bore 370 of the ports 37a in the loading sleeve 28, Another port 380 leads into the pressure chamber 38 from the outside of the loading sleeve 28 and is adapted to be closed by a plug 38b which is threadedly engaged in a threaded bore 38c in the loading sleeve 28. This port 38a allows the bleeding off of any fluid from within the chamber 38 when the tool assembly is being conditioned for running by applying pressure into the chamber 37, whereupon the plug 38b may be installed to close off the chamber 38 from the escape of fluid outwardly from the loading sleeve 28.

Following landing of the hanger body 10 on the shoulder 13 of the body J and cementing of the casing Y in place, as hereinafter described, the sleeve 41 will be pulled from the mandrel passage 20 by a suitable recovery tool, as is well known in the oil well equipment field, and will be recovered from the upper end of the drill pipe 19.

Thereafter, a loading dart, generally denoted at 70 in FIG. 3a, will be lowered through the drill string 19, or dropped therethrough, so as to land upon the internal shoulder 42 within the mandrel passage 20. This dart 70 includes an elongate body 71 having a lower cylindrical section 72 provided with a side seal ring 73 adapted to sealingly engage within the mandrel passage 20 below the lower ports 39. The dart body 71 also has an upper cylindrical section 74 provided with side seal rings 75 adapted for sealing engagement within the bore 20 of the mandrel 16 above and below the upper ports 40. The dart body 71, in its lower end section 72, has a transverse passage or passages 76, which communicates with the ports 39 and with a downwardly opening central passage 78 leading into the mandrel bore 20 at the bottom of the dart 70. The upper cylindrical section 74 of the dart 70 has a suitable number of radial passages or ports 79 communicating with the ports 40 and with a like number of upwardly extending passages 80 which open upwardly into the mandrel bore 20. At its upper end, the body 71 of the dart 70 has a fishing neck 81 provided with an enlarged head 82, which has a downwardly facing shoulder 83, whereby the dart 70 may be engaged by a suitable fishing tool (not shown) and pulled from the mandrel passage 20 upwardly through the drill pipe 19, when desired.

With the dart 70 in place, as shown in FIG. 3a, the lower chamber 36 between the piston 26 on the mandrel 16 and the internal cylinder head 33 of the loading sleeve 28 may exhaust into the mandrel passage 20 below the dart, and the upper chamber 38 between the loading sleeve head 33 and the upper piston 27 is in communication with the mandrel passage 20 above the dart. Therefore, fluid under pressure may be supplied to the chamber 38 through the ports 80, 79 and 40, so as to apply fluid pressure to the head 33 to force the loading sleeve 28 downwardly, the liquid in the lower chamber 36 exhausting through the passages 39, 76, 78. Such downward movement of the loading sleeve 28 will cause corresponding downward movement of the seal support ring 50 and the deformable seal means 55 carried thereby, causing engagement of the deformable metal lock fingers 59 with an inclined or conical expander surface 59a of the portion of the hanger body 10 providing the supporting shoulder 12, which will effect outward expansion and deflection of the lock fingers 59 into the channel 60 of the body J. The application of further and increased pressure in the chamber 38 will shear the pin 52 and contact the shoulders 54, 53, further downward movement of the support ring 50, following outward deflection or deformation of the lock fingers 59, causing foreshortening of the undulated sleeve section 56 and movement of its crests toward the walls a, 10b of the hanger bodies 10 and J, and deformation of the elastomeric body 57 into tight sealing contact with the opposing cylindrical walls 10a and 10b of the hanger body 10 and the outer hanger body J.

The lock fingers 59 and the undulated sleeve portion 56 of the means 55 may be composed of mild steel or other malleable material, which, when expanded as illustrated in FIG. 3b, for example, will be deformed beyond their elastic limit and will retain their deformed shape. Thus, the undulated section 56 of the seal means 55 will be so deformed so as to effect virtual metal-to-metal contact between the inner crests 56a and the outer crests 56b of the undulated sleeve section 56. Under these circumstances, the elastomeric material 57 will fill the spaces between the undulations to assist in the prevention of leakage. A slight thickness of elastomeric material might be trapped between the crests 56a, 56b and the cylinder walls 10a, 10b.

The sealing relation between the inner crests 56a and the outer crests 56b of the undulated seal sleeve section 56 is more particularly illustrated in FIG. 5, in which the elastomeric material 57 is also shown as being caused to extrude into and fill the spaces between the adjacent undulations.

As seen in FIG. 6, a modified seal construction is illustrated in which an undulated seal sleeve section 156 is illustrated, having at least one inner crest 156a and at least one outer crest 15612 deformed, in response to axial compressive force applied thereto, into tight sealing engagement with the opposing cylindrical walls 10a and 10b. The undulations or corrugations in either of the seal sleeves 56 or 156 are circumferentially continuous, so that the inner crests 560 or 156a and the outer crests 56b or 15612, as the case may be, will effect circumferentially continuous inner and outer sealing engagement with the opposed cylindrical walls.

In the use of the apparatus, the casing hanger assembly, with the loading sleeve 28 in the upper position of FlGS. 2a and 2b and with the sealing sleeve 41 in place, is connected to the threaded pin 18 of the drill pipe 19, so as to be lowered through the body of water into seating engagement with the shoulder 13 in the previously set hanger body or casing J. Thereafter, a circulating fluid may be displaced downwardly through the drill pipe 19, passing through the mandrel passage 20 and downwardly into the casing Y, thence upwardly through the annulus 21 and then flowing through the ports 22 of the hanger body 10, upwardly through the seal means 25 into a space between the mandrel 16 and the loading sleeve 28. Below the piston 26 on the mandrel l6, circulating fluid will pass through ports 28a externally of the loading sleeve 28 and thence may flow upwardly into the space between the loading sleeve 28 and the casing hanger body J.

Following the circulation of suitable well conditioning fluid for the desired period of time, a quantity of pumpable cement slurry may be displaced downwardly through the pipe 19 behind the circulating fluid and may follow a similar course until the quantity of cement slurry has been displaced to fill or substantially fill the annulus 21. Thereafter, a suitable recovery tool will be run into the pipe 19 and engaged with the flange 47 of the seal sleeve 41, and the seal sleeve 41 recovered. The dart 70 will then be dropped into the pipe 19, or, if necessary, run into a seated position within the mandrel 16 so as to allow the application of fluid pressure to the upper pressure chamber 38 and the exhaust of the lower chamber 36. In response to the application of such fluid pressure in the upper chamber 38, the loading sleeve 28 will be forced downwardly, moving the seal means 25 and the anchor means 23 downwardly, effecting the outward deformation of the lock fingers 59, as previously described, and also effecting axial and circumferential deformation of the metallic undulated seal ring 56 and the elastic body 57, if the seal ring includes such elastomeric material, the shear pins 52 being disrupted prior to application of maximum pressure to the cylinders 28, 33 in effecting a leak-proof seal. The application of appropriate fluid pressure in the chamber 38 will complete expansion of the sealing means 25 and locking of the fingers 59 in the groove 60, whereupon the entire mnning tool Z will be free for recovery from the hanger body 10.

In order to recover the running tool Z, the running string of pipe will be rotated to the right to disconnect the left-hand threaded connection between the flange 15 of the tool mandrel 16 and the internally threaded section 14 of the hanger body 10. When the left-hand thread is disconnected, upward movement of the running string 19 will move the tool mandrel 16 upwardly until the piston 26 thereon engages the head 33 of the loading sleeve 28 to lift the latter, permitting the entire assembly to be moved upwardly from the casing head or hanger body J, minus the hanger body 10, and the packed-oft and anchored seal means 25. Prior to elevating the running tool Z, it is desirable to remove the dart from the mandrel 16 to permit the fluid in the drill pipe 19 to drain during its elevation to the drilling rig.

Iclaim:

1. In sealing apparatus: an inner member; an outer member surrounding said inner member and spaced therefrom to define an annular space therebetween; and seal means in said annular space and including an annular body of elastomeric material, an axially deformable metallic ring of axially undulant form having inner and outer annular portions embedded in said annular body and respectively inwardly and outwardly deformable toward said inner member and said outer member upon axial deformation of said ring to sealingly engage said annular body with said inner and outer members.

2. In sealing apparatus as defined in claim 1; stop means engageable by said seal means to prevent axial movement of one end of said seal means whereby axial force imposed on the other end of said seal means effects said axial deformation of said ring.

3. In sealing apparatus as defined in claim 1; first stop means on one of said members engaged by second stop means on said seal means to prevent axial movement of one end of said seal means whereby axial force imposed on the other end of said seal means effects said axial deformation of said ring.

4. In sealing apparatus as defined in claim 1; stop means engageable by said seal means to prevent axial movement of one end of said seal means whereby axial force imposed on the other end of said seal means effects said axial deformation of said ring; a member at said other end of said seal means and shiftable along said members; and means for shifting said shiftable member toward said stop means to deform said ring and annular body between said stop means and axially shiftable member.

5. In sealing apparatus an inner member; an outer member surrounding said inner member and spaced therefrom to define an annular space therebetween; and seal means in said annular space and including an axially deformable metallic ring of axially undulant form having inner and outer annular portions respectively inwardly and outwardly deformable into sealing relation with said inner member and said outer member upon axial deformation of said ring; first stop means on one of said members engaged by second stop means on said seal means to prevent axial movement of one end of said seal means whereby axial force imposed on the other end of said seal means effects said axial deformation of said rings; said second stop means having a plurality of circumferentially spaced longitudinally extending lock fingers, said first stop means including a recess in said one member for receiving said fingers, and said other member having means for deforming said fingers laterally into said recess.

6. In a sealing device: an axially extended malleable metallic ring having axial undulations forming an inner circumferentially continuous crest and an outer circumferentially continuous crest respectively inwardly and outwardly deformable toward opposing cylindrical walls in response to axial deformation of said ring, and an annular body of continuous crest respectively inwardly and outwardly deformable toward opposing cylindrical walls in response to axial deformation of said ring; a plurality of circumferentially spaced deformable lock fingers extending axially from said ring, said lock fingers being deformable laterally for locking engagement with a companion member.

* i it: 

1. In sealing apparatus: an inner member; an outer member surrounding said inner member and spaced therefrom to define an annular space therebetween; and seal means in said annular space and including an annular body of elastomeric material, an axially deformable metallic ring of axially undulant form having inner and outer annular portions embedded in said annular body and respectively inwardly and outwardly deformable toward said inner member and said outer member upon axial deformation of said ring to sealingly engage said annular body with said inner and outer members.
 2. In sealing apparatus as defined in claim 1; stop means engageabLe by said seal means to prevent axial movement of one end of said seal means whereby axial force imposed on the other end of said seal means effects said axial deformation of said ring.
 3. In sealing apparatus as defined in claim 1; first stop means on one of said members engaged by second stop means on said seal means to prevent axial movement of one end of said seal means whereby axial force imposed on the other end of said seal means effects said axial deformation of said ring.
 4. In sealing apparatus as defined in claim 1; stop means engageable by said seal means to prevent axial movement of one end of said seal means whereby axial force imposed on the other end of said seal means effects said axial deformation of said ring; a member at said other end of said seal means and shiftable along said members; and means for shifting said shiftable member toward said stop means to deform said ring and annular body between said stop means and axially shiftable member.
 5. In sealing apparatus: an inner member; an outer member surrounding said inner member and spaced therefrom to define an annular space therebetween; and seal means in said annular space and including an axially deformable metallic ring of axially undulant form having inner and outer annular portions respectively inwardly and outwardly deformable into sealing relation with said inner member and said outer member upon axial deformation of said ring; first stop means on one of said members engaged by second stop means on said seal means to prevent axial movement of one end of said seal means whereby axial force imposed on the other end of said seal means effects said axial deformation of said rings; said second stop means having a plurality of circumferentially spaced longitudinally extending lock fingers, said first stop means including a recess in said one member for receiving said fingers, and said other member having means for deforming said fingers laterally into said recess.
 6. In a sealing device: an axially extended malleable metallic ring having axial undulations forming an inner circumferentially continuous crest and an outer circumferentially continuous crest respectively inwardly and outwardly deformable toward opposing cylindrical walls in response to axial deformation of said ring, and an annular body of elastomeric material in which said metallic ring is embedded, whereby inward and outward deflection of said crests sealingly engages said annular body with the opposing cylindrical walls.
 7. In a sealing device as defined in claim 6; a plurality of circumferentially spaced lock fingers extending axially from said ring, said lock fingers being deformable laterally for locking engagement with a companion member.
 8. In a sealing device: an axially extended malleable metallic ring having axial undulations forming an inner circumferentially continuous crest and an outer circumferentially continuous crest respectively inwardly and outwardly deformable toward opposing cylindrical walls in response to axial deformation of said ring; a plurality of circumferentially spaced deformable lock fingers extending axially from said ring, said lock fingers being deformable laterally for locking engagement with a companion member. 